This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The specific aims of this study are to better understand the mechanisms regulating norepinepherine release during exercise by using microdialysis techniques to determine interstitial norepinephrine in skeletal muscle.